U.S. Pat. No. 4,281,607 shows a cutting device of such type wherein the blade on the one hand and the blade cover on the other hand are separately driven by separate drives in form of pneumatically operated piston-cylinder-drives. The actuation of these drives is accomplished in such a manner, that at first the blade will be moved to the cutting position if the blade guard has been moved in a position close to the cutting zone, so that the operator cannot get his fingers into the operating path of the blade. Such an electric sequential control for operating the piston-cylinder-drives includes the risk of malfunctions. Moreover, the required separate drive for the blade guard includes additional risk of injury due to its dimensioning and operation.
German Offenlegungsschrift No. 27 19 894 shows a cutting device for a sewing machine, wherein a blade is driven via a toggle mechanism, an intermediate joint of which is drivably connected to a piston rod of a pneumatically operated piston-cylinder-drive. While one end of the toggle mechanism is linked to the blade, the other end of the toggle mechanism is stationarily suspended. Upon one single motion of the piston rod in one direction the blade will be moved from an upper inoperative position towards a counter knife while performing the cutting process, wherein the latter is achieved in a stretched position of the toggle mechanism. Upon further linear motion of the piston rod the toggle mechanism is kinked in or folded again, i.e. the blade is restored into its upper inoperative position.